The adenoviral early 4 (E4) region contains at least 6 open reading frames (E4ORFs). The entire E4 region has been shown to regulate angiogenesis and promote survival, but not proliferation, of endothelial cells (see, for example, Zhang et al. (2004), J. Biol. Chem. 279(12):11760-66). Prior to the present invention, it was not known whether all of the ORFs within the E4 region, a subset of the E4ORFs, or a single specific E4ORF, might be responsible for this activity. Use of the entire E4 region, either clinically or experimentally, to induce angiogenesis or to promote survival or proliferation of endothelial cells, may not be desirable because some of the E4ORFs can have deleterious effects. For example, the E4ORF6 gene is known to induce apoptosis (Yamano et al. (1999) J. Virol. 73:10095-103). Also, the E4ORFs are immunogenic and therefore administration of all of the E4ORFs to subjects may not be desirable. Accordingly, there was a need in the art to identify the sequences within the E4ORF region responsible for its pro-angiogenic and pro-endothelial cell survival effects. The present invention solves this problem in the art by identifying sequences within the E4ORF region that are useful for inducing angiogenesis and for promoting survival and proliferation of endothelial cells.